The present invention relates to printing devices. More particularly, the present invention relates to a media detector for and a method of differentiating between transparent and nontransparent print media.
Printing devices, such as inkjet printers, use printing composition (e.g., ink or toner) to print text, graphics, images, etc. onto print media. The print media may be of any of a variety of different types including transparencies, standard document paper, letter quality paper, envelopes, photographic print stock, cloth, etc. These print media may be placed in one of two broad categories relating to the amount of light that is transmitted through the particular print media. The first category is transparent print media, such as overhead transparencies that are used with an overhead projector and screen. The second category is nontransparent print media, such as standard document paper, letter quality paper, envelopes, photographic print stock, cloth, etc. A transparent print media is specifically defined herein as having the property of transmitting visually perceptible light signals through such media substantially unattenuated when the visually perceptible light signals are substantially orthogonally incident to either surface of such print media. A nontransparent print media is specifically defined herein as having the property of substantially diffusing and attenuating visually perceptible light signals incident to either surface of such print media. Transparent and nontransparent print media each have various characteristics that ideally should be accounted for during printing, otherwise a less than optimal printed output may occur.
One way in which a printing device can be configured to a particular print medium is to have a user make manual adjustments to the printing device based upon these characteristics and factors. One problem with this approach is that it requires user intervention which is undesirable. Another problem with this approach is that it requires a user to correctly identify various characteristics of a particular print medium. A further problem with this approach is that a user may choose not to manually configure the printing device or may incorrectly manually configure the printing device so that optimal printing still does not occur in spite of user intervention. This can be time-consuming and expensive depending on when the configuration error is detected and the cost of the particular print medium.
A device and method that automatically differentiates between transparent and nontransparent print media would be a welcome improvement. Accordingly, the present invention is directed to alleviating these above-described problems and achieving this end. The present invention accomplishes this without degrading output print quality of the printing device.
An embodiment of a print media detection system in accordance with the present invention for use in a printing device includes a source and a sensor. The source is configured to transmit a light signal and the sensor is configured to detect the light signal and generate an electrical signal in response to the light signal. The electrical signal has a magnitude that increases up to a substantially constant value as an intensity of the light signal from the source increases. The sensor is also configured to generate the electrical signal with a first magnitude for a transparent print media through which the light signal from the source travels to the sensor. The sensor is additionally configured to generate the electrical signal with a second magnitude less than the first magnitude for nontransparent print media positioned in a path of the light signal from the source to the sensor.
The above-described print media detection system in accordance with the present invention may be modified and include the following characteristics described below. The print media detection system may further include a controller coupled to the sensor. The controller is configured to receive the electrical signal from the sensor and, based at least in part on the electrical signal, control an operating parameter of the printing device.
The source may include a focused light emitting diode. The sensor may include a phototransistor. The print media detection system may be used in a printing device.
An alternative embodiment of a print media detection system in accordance with the present invention for use in a printing device includes structure for transmitting a light signal. The print media detection system also includes structure for sensing the light signal and producing an electrical signal having a first magnitude for a transparent print media through which the light signal travels and a second magnitude less than the first magnitude for nontransparent print media positioned in a path of the light signal from the source to the sensor.
The above-described alternative embodiment of a print media detection system in accordance with the present invention may be modified and include the following characteristics described below. The print media detection system may further include structure, coupled to the structure for sensing, for controlling an operating parameter of the printing device based at least in part on the electrical signal received from the means from sensing.
The structure for transmitting may include a focused light emitting diode. The structure for sensing may include a phototransistor. The print media detection system may be used in a printing device.
An embodiment of a method of detecting transparent and nontransparent print media in accordance with the present invention for use in a printing device includes transmitting a light signal toward a sheet of print media. The method also includes measuring an intensity of light at a sensor positioned along a path of the light signal, the sheet of print media being positioned between the light signal and the sensor. The method further includes generating either an electrical signal having a first magnitude for a measured intensity of light substantially equal to an intensity of the light signal or an electrical signal having a second magnitude less than the first magnitude for a measured intensity of light less than the intensity of the light signal.
The above-described method in accordance with the present invention may be modified and include the following characteristics described below. The method may further include controlling an operating parameter of the printing device based at least in part on the electrical signal.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.